Shortened links and 301 redirects

We allow visitors to access our pages through the use of a short numeric identifier for each page. This is basically the unique ID in the database for that specific information. However, as soon as they visit that page using the shortened link they are redirected to the page as the link would show up on the site normally via a 301 Permanent Redirect.

These links have started showing up in forums and various pages, however, I am concerned about what will happen to our ranking from doing a 301 Permanent Redirect on these. Is this a good idea?

Also, will having an alternate link for a specific page impact the Google page rank of that page if most of the incoming links for it are these shortened links?

301 permanent redirect is the only method that will work for this scenario. It should be fine. A 301 passes your value for the page and everything so will pass your PR as well.

It just occurred to me that even though we print the shortened link a plain text that Google will snap that up and visit the link even though it isn't in an HREF attribute.

Any way to prevent the search engines from seeing that without encoding it with JavaScript?

usually, most of tiny url sites use 302 redirect [IMHO ]